Coupling device for coupling a frictional damper to a machine frame of a washing machine

ABSTRACT

The invention relates to a coupling device ( 19 ) for coupling a frictional damper with a middle longitudinal axis ( 21 ), which is coupled to an oscillatory washing unit with a drum axis, to a machine frame of a washing machine with a spin gear. The coupling device has a first bending axis, which runs vertically to the central longitudinal axis ( 21 ) and parallel to the drum axis, a second bending axis ( 33 ) which runs vertically to the central longitudinal axis ( 21 ) and to the first bending axis and intersects both at one point, a first connecting element for connecting the coupling device ( 19 ) to the frictional damper, a second connecting element for connecting the coupling device ( 19 ) to the machine frame and a spring element ( 24 ) that is located between the first connecting element and the second connecting element and is connected to both, the flexural strength of the coupling device ( 19 ) about the second bending axis ( 33 ) being greater than the flexural strength about the first bending axis.

REFERENCE TO RELATED APPLICATIONS

The present application is the national stage under 35 U.S.C. §371 ofinternational application PCT/EP00/03882, filed Apr. 28, 2000, whichdesignated the United States, and which application was not published inthe English language.

The invention relates to a pivotable connection device for pivotableconnection of a friction damper to a machine frame of a washing machine,with a spin cycle.

It is known, for instance from European Patent Disclosure EP 0 336 176B1 (corresponding to U.S. Pat. No. 4,934,493), in washing machines witha spin cycle, to damp the washer assembly relative to the machine frameusing friction dampers. The friction dampers are pivotably connectedrelative to the machine frame via pivotable connection devices. In thesimplest case known by public prior use, the pivotable connectiondevices are embodied cylindrically of an elastic material and solidlyconnected on the one hand to the tappet of the friction damper and onthe other to the machine frame of the washing machine. In spinning,oscillations of the washer assembly occur parallel to and perpendicularto the drum axis, along with tumbling motions of the washer assembly,leading to variously pronounced deflections of the pivotable connectionpoint between the friction damper and the washer assembly parallel tothe drum axis and perpendicular to it. A disadvantage of the knownpivotable connection devices is that pivotable connection of thefriction dampers to the machine frame cannot be done to suit theintensity of the individual components of the oscillations.

From U.S. Pat. No. 4,729,458, a friction damper for a washing machine isknown. On its free ends, it has pivotable connection devices, whichsubstantially comprise it rectangular rubber plate. The edges of therectangle are of ditferent lengths, so that the damping about a firstbending axis is different from the damping about a second bending axisthat extends perpendicular to the first. A disadvantage here is that theratio of the damping characteristics is adjustable only within a verynarrow range, since because of the strength of the rubber and because ofthe space available for the pivotable connection device, very narrowconditions are necessarily set. Furthermore, the damping behavior of thepivotable connection device along the central longitudinal axis of thefriction damper is essentially not adjustable.

From U.S. Pat. No. 3,509,742, a spring leg for a washing machine isknown which is joined to the washer assembly and to the machine framevia two pivotable connection devices. The pivotabic connection devicesubstantially comprises two rectangular rubber plates one above theother Once again, adjusting the ratio of the flexural strength about afirst bending axis to the flexural strength about a bending axisextending perpendicular to it is quite limited. Furthermore, the dampingbehavior of the pivotable connection device along the centrallongitudinal axis of the spring leg is essentially hardly adjustable.

The object of the invention is to furnish a pivotable connection devicefor pivotable connection of a friction damper to the machine frame of awashing machine with a washer assembly, which enables a pivotableconnection that corresponds to one of the individual components oftumbling motions of the washer assembly.

This object is attained by the characteristics of the body of claim 1.The nucleus of the invention is to furnish a pivolable connection devicein which the flexural strength, that is, the contrary force occurringupon sagging, upon a deflection parallel to the drum axis of the washerassembly is greater than upon a deflection perpendicular to the drumaxis.

Further advantageous features of the invention will become apparent fromthe dependent claims.

Additional characteristics and details of the invention will becomeapparent from the description in conjunction with the drawing, Shownare:

FIG. 1 a drum-type washing machine, in a schematic side view, with afriction damper and a pivotable connection device;

FIG. 2 a drum-type washing machine of FIG. 1 in a front view;

FIG. 3 an enlarged detail of the friction damper and the pivotableconnection device in the view of FIG. 2;

FIG. 4 a view of the pivotable connection device in the direction of thearrow IV in FIG. 3; and

FIG. 5 a cross-sectional view taken along the section line V—V in FIG.4.

A drum-type washing machine with a horizontal drum axis has a vibratablewasher assembly 2 with a drive motor 3, which, drives the washing drum,not shown in detail, via a belt drive 4. Other components, such as agear, that are connected to the washer assembly 2 are not shown, for thesake of simplicity. The vibratable washer assembly 2 is suspended from awashing machine housing 6, braced on a machine frame 5 formed by a baseframe, by means of helical tension springs 7. The tension springs areattached on the one hand to eyelets, mounted in the upper region of thewasher assembly 2. On the other, they are suspended from eyelets 9 thatare embodied on side walls 10 of the housing 6. Instead of this kind ofsuspension of the washer assembly 2 from tension springs 7, bracing thewasher assembly 2 in a known manner via so-called spring legs on themachine frame 5 can also be provided, as known from European PatentDisclosure EP 0 108 217 B1 (corresponding to U.S. Pat. No. 4,991,412).What is decisive is that the washer assembly 2 be suspended or braced ina way that leaves it free to vibrate.

Between the washer assembly 2 and the machine frame 5, friction dampers11 are also provided, which are known for 20. instance from EP 0 336 176B1 (corresponding to U.S. Pat. No. 4,934,493). Each friction damper 11has a housing 12. The housing 12 substantially comprises a cylindricaltube 13, which is closed on one end by a bottom 14. An articulated bush15 in the form of a pivotable connection element is mounted on theoutside of the bottom 14, and by means of it the friction damper 11 ismounted on a bearing 16 on the washer assembly 2 in such a way that thefriction damper 11 is mounted so that it is pivotable about a pivot axis17 relative to the washer assembly 2, which pivot axis extends parallelto the drum axis 1. The applicable friction damper 11 also has a tappet18, which on its outer end has an elastic pivotable connection device19. The friction damper 11 and the pivotable connection device 19 have acommon central longitudinal axis 21. Via the pivotable connection device19, the friction damper 11 is joined to a connecting base 22 that ismounted on the machine frame 5. In succession along the centrallongitudinal axis 21, the pivotable connection device 19 has a tappetconnection stopper 23 embodied as a first connection element, a tubularspring element 24, and a frame connection stopper 25 embodied as asecond connection element, all three of which are embodied in one piece.The stopper 23 is embodied essentially circular-cylindrically with adiameter D_(S) and concentrically to the axis 21, and on its free end ithas a blind bore 26 to increase the deformability of the stopper 23radially to the axis 21. For joining the stopper 23 to the tappet 18,the latter substantially comprising a thin-walled metal tube 27, thestopper 23 has an annular groove 28 as well as a stop edge 29 that isdownstream in the direction of the spring element 24. The tube 27 islocated on one end in contact with the stop edge 29 and is secured tothe stopper 23 by a bead 30 embodied in the tube 27 and extendingradially to the axis 21. The spring element 24 is joined to the stopper23 via a connecting rib 31. The spring element 24 is embodied annularlycylindrically and concentrically to a first bending axis 32, whichintersects the axis 21 perpendicular to it and extends parallel to thedrum axis 1. An axis extending perpendicular to the axes 21 and 32 andintersecting both of them at one point is called a second bending axis33. It is also possible to provide spring elements 24 with an ellipticalor rectangular cross-sectional profile or some arbitrary other profile.The length LF of the spring element 24 parallel to the axis 32 isgreater than the outside diameter D_(A) of the spring element 24parallel to the bending axis 33. The applicable relationships are:L_(F)/D_(A)≧1.5, and in particular L_(F)/D_(A)>2. For the ratio of theoutside diameter D_(A) to the inside diameter of the spring element 24,the following is true: D_(A)/D_(I)≈1.4. For the width B_(V) of theconnecting rib 31 parallel to the bending axis 33, it is true thatB_(V)≦D_(A), B_(V)≦D_(S), and in particular B_(V)≦D_(I). The lengthL_(V) of the connecting rib 31 parallel to the bending axis 32 decreasessteadily from the length L_(F) of the spring element 24 to the outsidediameter D_(R) of the tube 27. On the side of the spring element 24opposite the connecting rib 31, a connecting rib 34 is provided, by wayof which the stopper 25 is joined to the spring element 24. For thewidth B_(S) of the connecting rib 34 parallel to the bending axis 33,the following is true: B_(S)≈B_(V), and in particular B_(S)≦B_(V). Onthe ends pointing in the direction of the bending axis 32, theconnecting rib 34 has longitudinal grooves 35. The stopper 25 isembodied essentially annularly cylindrically and concentrically to theaxis 21 and has a diameter D_(G) of which it is true that B_(S)≦D_(G).In a first embodiment, shown in the left-hand half of FIG. 5, it hascircumferentially disposed, radially outward-protruding detent lugs 36,which narrow toward the free end of the stopper 25. The connecting base22 has an annular-cylindrical wall 37 with detent openings 38, which areengaged by the detent lugs 36 and lock the pivotable connection device19 against tension relative to the machine frame 5. In a secondembodiment, shown in the right-hand half of FIG. 5, the stopper 25 hasan annular groove 39 on its circumference. Instead of the annular groove39, individually recesses could also be provided. Individual lockingarms 40, which lock the pivotable connection device 19 against tensionrelative to the machine frame 5, are joined integrally to the wall 37and engage the annular groove 39. The pivotable connection device 19 isfabricated from a thermoplastic polyelastomer or a thermoplasticpolyurethane. Other flexible materials can also be used. In particular,it is also possible for only the spring element 24 to comprise anelastic material. Instead of the articulated bush 15, it is alsopossible to provide a pivotable connection device 19 which in that caseis joined on the one hand to the housing 12 and on the other to thewasher assembly 2. It is possible to provide a pivotable connectiondevice 19 according to the invention in which the variables D_(S),D_(R), B_(V), D_(A), D_(I), B_(S), D_(G), L_(F), L_(V) deviate from theproportions given above.

The mode of operation of the pivotable connection device 19 will now bedescribed. In operation of the washer assembly 22 in the spin cycle, notonly vibrations perpendicular to the drum axis 1 but also parallel to itoccur, namely pitching vibrations, and corresponding superpositions ofboth types, or in other words tumbling motions. For the most part, thesemotions are damped by the friction dampers 11. Because of the vibrationsof the washer assembly 2, the articulated bush 15 is displaced, andhence a bending moment acts on the pivotable connection device 19.Because of the above-described design of the pivotable connection device19, it has a flexural strength about the bending axis 32 that is lessthan the flexural strength about the bending axis 33. This is dictatedby the tubular structure of the spring element 24, and the ratio of thetwo flexural strengths can be adjusted freely by varying the dimensions.The flexural strength about the bending axis 32 relative to the flexuralstrength about the bending axis 33 is reduced by the provision ofconnecting ribs 31 and 34 that are narrow relative to the outsidediameter D_(A). This means that vibrations parallel to the drum axis 1will be damped more markedly than vibrations perpendicular to the drumaxis 1. Remaining vibrations that are not damped by the friction damper11, and in particular vibrations parallel to the axis 21, are damped bya deformation of the spring element 24. It is thus possible by means ofthe pivotable connection device 19 for a friction damper 11, deflectedin various directions with variously strong force, to be pivotablyconnected to the machine frame 5 in a manner appropriate for themagnitude of the forces.

What is claimed is:
 1. A pivotable connection device (19) for pivotableconnection of a friction damper (11), which has a central longitudinalaxis (21) and is pivotably connected on a washer assembly (2) that has adrum axis (1) and is supported in a manner capable of vibration, to amachine frame (5) of a washing machine (2) with a spin cycle, having a)a first bending axis (32), which extends perpendicular to the centrallongitudinal axis (21) and parallel to the drum axis (1); b) a secondbending axis (33), which extends perpendicular to the centrallongitudinal axis (21) and to the first bending axis (32) and intersectsthem both at one point; c) a first connection element for connecting thepivotable connection device (19) to the friction damper (11); d) asecond connection element for connecting the pivotable connection device(19) to the machine frame (5); and e) a spring clement (24), disposedbetween the first connection element and the second connection elementand connected to both of them; f) wherein the flexural strength of thepivotable connection device (19) about the second bending axis (33) isgreater than the flexural strength about the first bending axis (32),characterized in that g) the spring element (24) is embodied in tubularform.
 2. The pivotable connection device (19) of claim 1, characterizedin that the spring element (24) is embodied concentrically to the firstbending axis (32).
 3. The pivotable connection device (19) of claim 1,characterized in that the spring element (24) is connected to the firstconnection element via a first connecting rib (31).
 4. The pivotableconnection device (19) of claim 3, characterized in that the width B_(V)of the first connecting rib (31), referred to the second bending axis(33), is less than the diameter D_(S) of the first connection element.5. The pivotable connection device (19) claim 1, characterized in thatthe spring element (24) is connected to the second connection elementvia a second connecting rib (32).
 6. The pivotable connection device(19) of claim 5, characterized in that the width B_(S) of the secondconnecting rib (34), referred to the second bending axis (33), is lessthan the diameter D_(G) of the second connection element.
 7. Thepivotable connection device (19) of claim 1, characterized in that theoutside diameter D_(A) of the spring element (24) perpendicular to thefirst bending axis (32) is less than the length L_(F) of the springelement (24) parallel to the first bending axis (32).
 8. The pivotableconnection device (19) of claim 1, characterized in that the firstconnection element and the spring element (24) and second connectionelement are embodied in one piece.
 9. The pivotable connection device(19) of claim 1, characterized in that the spring element (24) is formedof thermoplastic elastomers or thermoplastic polyurethanes.